Photo-sensitive devices such as imager devices are used in many applications and variations. In addition to solid state imagers like CCD (charge coupled devices) imagers or CMOS (Complementary Metal Oxide Semiconductor) imagers which are capable of providing 2D (2 dimensional) images, 3D imager or depth imagers are becoming increasingly popular for multiple applications. For 3D imaging and depth imaging, optical sensors based on time-of-flight (TOF) are very promising for future applications ranging from the taking of a profile of objects or environments, the tracking and recognition of objects and human beings to the recognition of movements of certain parts or gesture recognition.
In applications of TOF sensors as well as for other optical imagers, the transfer of charge is crucial to the operation of the imager. To give one example, for the demodulation of incoming light provided by devices which are based on the time-of-flight principle the timely transfer of charge carriers to the read-out nodes is critical for the accuracy of the depth information as well as other operation parameters.